The present invention relates to ultraviolet water purification systems and is directed more particularly to an improved monitoring port for facilitating measurements of the intensity of ultraviolet radiation at selectable positions within the purification system.
In order to purify water which is contaminated by bacteria, it is a common practice to direct the water through a purification system which exposes the water to ultraviolet (UV) radiation. Because UV radiation is able to kill bacteria, the water emerging from such a purification system has a greatly reduced live bacteria content and can often be safely used without further treatment.
Because the effectiveness of UV purification systems is dependent upon the ability of a UV lamp or lamps to apply more than a predetermined intensity of UV radiation to the water for more than a predetermined time, such systems are usually provided with UV monitoring arrangements for measuring the UV output of the lamps. Such monitoring arrangements include UV sensitive electronic devices which are coupled to respective UV lamps through respective UV transparent monitoring ports or windows that penetrate the external walls of the purification system. One such monitoring arrangement is described in U.S. Pat. No. 3,471,693, which issued in the name of L. P. Veloz on Oct. 7, 1969.
In some UV purification systems, the UV monitoring arrangement is arranged to measure the level of UV radiation which exists near the surface of a UV lamp. Monitoring arrangements of this type have monitoring ports with inlets that are located at or near the outer surface of the lamp itself, or near the outer surface of a quartz tube or envelope that surrounds the lamp and protects the same from exposure to the water to be purified. In other UV purification systems, the monitoring arrangement has a monitoring port with an inlet that is located in the fluid retaining wall of the system. In systems of the latter type, radiation is incident on the monitoring arrangement only after passing through the water to be purified.
Both of the above types of monitoring arrangements have deficiencies which limit the usefulness of the output information provided thereby. The problem with a monitoring arrangement which has an inlet that is close to the surface of a lamp is that the UV sensitive electronic device is unable to determine whether the UV radiation intensity at points more distant from the surface of the lamp is adequate to assure complete purification. The problem with a monitoring arrangement which has an inlet that is located at the fluid retaining wall of the system is that it allows a user to take measurements only through a fixed depth of liquid. As a result, such an arrangement prevents a user from measuring the UV radiation intensity at other distances from the surface of the UV lamp. A UV purification system which has UV monitoring arrangements of both types is shown in U.S. Pat. No. 4,336,223, which issued on June 22, 1982 in the name of L. Hillman.